Spotlight searches with "and" logic. The item you are looking for has to be all of these types to be found. If Spotlight had the ability to use "or" logic and even nested parameters, all would be good.
If you save this smart folder and get info on it, the query will show && which means "and" logic. You can manually change the search parameters in the terminal apparently to || which means "or" but after you've done this, editing the parameters in Finder reverts back to "and" logic.
JayJay1974